Many machines are mobile machines that travel in order to perform one or more functions. For example, many earth moving machines move earth by traveling with an earth moving tool engaging the ground. In many circumstances a mobile machine may need to travel on or close to a particular path in order to properly perform a task. In many applications, mobile-machine navigation systems are employed to automatically adjust the heading of a mobile machine to keep the mobile machine close to such a target path as it travels. Many such mobile-machine navigation systems continually adjust the heading of a mobile machine whenever and as long as the mobile machine is not on a path, which may be a high percentage of the time the mobile machine is traveling. Such mobile-machine navigation systems may not be well-suited for some applications. For example, such a mobile-machine navigation system may cause undesirably rapid wear of the components of some skid-steer type steering systems by operating the steering system to make heading changes over an undesirably high percentage of the mobile machine's travel.
U.S. Pat. No. 5,925,080 to Shimbara et al. (“the '080 patent”) shows a drive control system for automatically navigating a vehicle along a predetermined path, wherein the drive control system implements a dead band for reducing the frequency of heading changes. The drive control system of the '080 patent is configured to sense the position of a guide means that extends along the predetermined path and control the heading of the vehicle dependent upon the position of the vehicle with respect to the predetermined path. As long as the vehicle remains within a dead band surrounding the predetermined path, the drive control system operates the steering system of the vehicle to direct the vehicle in a straight line. Whenever the vehicle is outside the dead band, the drive control system of the '080 patent continuously operates the steering system to change the heading of the vehicle at a rate dependent upon the distance between the vehicle and the predetermined path.
Although the drive control system of the '080 patent does not operate the steering system to change the heading of the vehicle when the vehicle is within the dead band, certain disadvantages persist. For example, by continuously changing the heading of the vehicle whenever the vehicle is outside the dead band, the drive control system may operate the steering system to change the heading of the mobile machine over a higher percentage of the vehicle's travel than may be desirable for some applications. Additionally, because the drive control system makes heading changes without regard to upcoming changes in direction of the predetermined path, the vehicle may frequently reenter the dead band with a heading that will quickly direct the vehicle back out of the dead band.
The mobile-machine navigation system and methods of the present disclosure solve one or more of the problems set forth above.